1. Field of the Invention
The present invention relates to the field of data processing, and in particular, to a method and apparatus for controlling the dissemination of digital information. Furthermore, the present invention provides transparent access to uncontrolled digital information together with controlled digital information with the same access apparatus.
2. Description of the Related Art
The distribution of original works--whether be it text, graphics, animation, video or audio--in magnetic, electronic, optical or any other medium is becoming popular. Advances in digital compression technology and improvement in the price/performance ratio of computers have made it economical and feasible to disseminate digital information in such "soft" forms. However, original works encoded in digital medium can be easily duplicated, encrypted, transmitted via communication networks and destroyed. For the remainder of the description of the present invention, original works encoded in digital medium shall be referred to as digital information. The push factors, i.e., easy access and manipulation, that make digital information a rival to the traditional hard copy forms, i.e., books, newspapers or microfiches, have also made it difficult to establish evidence of illegal usage of such information.
With respect to the distribution of hard copies of original works, copyright and publishing laws strike a balance between the twin goals of compensating the publisher/author and of maintaining reasonable cost to the end users. It is straightforward to establish evidence of making illegal copies of hard copy of original works. The main thrust of copyright and publishing laws is to establish evidence of illegal possession.
In contrast, evidence of illegal possession of digital information is difficult at best and at worst impossible to obtain. The present invention proposes to control the usage of distributed digital information as an alternative. By usage, the present invention refers to the number and timing of the accesses specified by the information provider.
Prior art controls the dissemination of software programs only with copy protection schemes. Copy protection relies on hardware or software artifacts to detect and prevent illegal copying of software programs. Encryption is sometimes used to provide copy protection. Some recent examples of copy protection schemes are U.S. Pat. No. 4,866,769 to Karp and U.S. Pat. No. 4,903,296 to Chandra et al.
U.S. Pat. No. 4,903,296 claims copy protection of software on magnetic medium with a special key having two marks made on the surface of the medium. These marks are in the form of absence of material and domains that cannot be formed by conventional magnetic disk write heads. Additionally, an encrypted key which is critical for running the application is built into a special purpose hardware subsystem. Finally the hardware subsystem is required to decrypt the key.
U.S. Pat. No. 4,866,769 teaches a method of copy protection of personal computer software distributed in diskettes through the use of a unique identification stored in read only memory of a personal computer. A source ID is provided with every software distributed. The personal computer ID is used with the source ID on the distribution diskette to produce an encoded check word, using any available encryption method. This check word is then used to verify that the software is being used on the designated personal computer.
While U.S. Pat. Nos. 4,903,296 and 4,866,769 disclose off-line schemes for controlled dissemination of software, U.S. Pat. No. 4,999,806 describes a central station distributing software over telephone lines--an on-line scheme for software dissemination. The central station transmits an acceptance code to a caller and then terminates the call. After verifying the caller's credit information, the central station calls the purchaser back and continues with the transaction only after receiving the acceptance code. The central station then transmits a Control Transfer Program and Initialization Program to the purchaser. The purchaser executes the Initialization Program to turn over control of the purchaser's computer to the central station. The Control Transfer Program makes sure that no memory resident copying programs are running before transmitting over the telephone line the purchased/leased program to the purchaser's computer. Thereafter the various transmitted programs are erased, leaving only a copy of protected version of the purchased program on the purchaser's disk.
To prevent unauthorized copying and use of information, prior art copy protection schemes require either introducing artificial indica as software keys or requiring special hardware subsystems. Not only are these solutions costly to both the information providers and the end users as they require additional processing steps, but they are also incompatible with the trend of encouraging concurrent use of different types of information in a network environment. Furthermore, the prior art copy protection schemes provide limited control over the dissemination of digital information in that they prevent unauthorized copying of software but not "uses" of such information.
Absent from the prior art is the dissemination of uncontrolled information. By uncontrolled information, the present invention refers to a portion of the information which the information provider has decided to let the end user view without registering it as a "use" of the controlled information. Typically, the uncontrolled information is either at a lower resolution compared with the controlled information or it comprises a selected portion of the controlled information which allows the end user to make an informed decision whether to subscribe or use the controlled information. Examples of uncontrolled information are the preview of a movie, or a demonstration version of the controlled software, or even an abstract of a patent document. Hitherto, prior art information dissemination system does not permit the transparent access of uncontrolled digital information with the same access device as that for accessing the controlled digital information.